In 1987, when the respondents were 11, 13, and 15 years of age, 28 percent of the males and 21 percent of the females reported having sexual experience with someone of the opposite sex. By the next year, when the respondents were 12, 14, and 16 years old, these figures had risen to 38 percent for males and 27 percent for females. Three percent of the females had experienced a pregnancy in the first year, while 11 percent had been pregnant by the second year. All the pregnancies were in females aged 13 or older. Among the 16-year-olds, 62 percent of the males and 57 percent of the females were sexually active, and 23 percent of the females had been pregnant at least once. Prevalence of early sexual activity across all cohorts was higher among blacks than among other ethnicities and among youths from single- parent families than those from intact families. Both the first and second waves of data indicated that youths involved in all levels of delinquency were more likely to be involved in sexual activity than were nondelinquents. Drug users were also much more likely to be sexually active. Data indicate the start of a developmental progression that for some individuals starts with delinquency and drug use and then moves to precocious sexual behavior and possibly to pregnancy. Figures